1. Field of the Invention
The present invention relates to a process for producing a connecting rod, and more particularly, to a process for producing a connecting rod which includes a connecting rod body having a larger end-forming semi-annular portion, and a semi-annular cap constituting a larger end in cooperation with the larger end-forming semi-annular portion, the semi-annular cap being abutted at its opposite circumferential end faces respectively against opposite circumferential end faces of the larger end-forming semi-annular portion and mounted to the latter.
2. Description of Related Art
Conventionally, as the above-mentioned process for producing a connecting rod, there is a known process including the steps of placing a sintered product for the connecting rod body and a sintered product for the semi-annular cap in a metal mold such that opposite circumferential end faces of the larger end-forming semi-annular portion of the sintered product for the connecting rod body and opposite circumferential end faces of the sintered product for the semi-annular cap are respectively opposed to each other; subjecting both the sintered bodies to a mold-forging process to provide a forged product including a connecting rod body and a semi-annular cap interconnected to each other; and subjecting the forged product to a fracturing process to provide the connecting rod body and the semi-annular cap which are fractured from each other (see German patent application Laid-open No. 3904020).
Because there exists a large number of voids on both the circumferential end faces of both the sintered bodies, a flow of plasticity of a material into the voids and a deformation of the voids can occur during a mold-forging process, and due to this, a large number of recesses and projections which fit to each other are formed on both the opposed circumferential end faces of the connecting rod body and the semi-annular cap. And by a subsequent fracturing process, these recesses and projections are fractured such as to be bisected into the recesses and projections.
The connecting rod obtained in the above-described manner has a merit in that when it is to be mounted to the semi-annular larger end portion of the semi-annular cap, it is possible to align both the members by fitting the recesses and projections to each other.
In such a conventional process, however, because both the sintered bodies are independent from each other, when they are to be mounted in the metal mold, there is a problem in that such mounting operation must be conducted individually, leading to an inferior workability.
Further, because the recess and projection of both the circumferential end faces are dependent on the voids existing on both the sintered bodies, there are problems in that the recess and projection are minute and their biting amount (biting amount means a height for the projection, and a depth for the recess, and so forth) are small and therefore, it is difficult to align the larger end-forming semi-annular portion and the semi-annular cap to each other and furthermore, both the members are apt to deviate from the right positions because their engaging force is weak.